One type of single fuel cell is described in Patent Literature 1. The single fuel cell described in Patent Literature 1 includes a hydrogen electrode and an oxygen electrode respectively on both sides of a MEA (membrane electrode assembly) and also includes a plate separator forming a hydrogen passage between the separator and the hydrogen electrode and another plate separator forming an oxygen passage between the separator and the oxygen electrode. Moreover, the single fuel cell includes a coolant passage portion on the oxygen electrode side.
The coolant passage portion includes two plate separators and a pre-load plate interposed between the two plate separators, and a space between the two plate separators is used as a passage of cooling water. The pre-load plate has a wave-shaped cross section and distributes a load locally generated due to form errors in constituent parts of the single fuel cell. The load is thereby evenly applied to the constituent parts.